Stripped Rocker Arm Bolt..what do to?

[koolkozak]

Hey guys, ran into a problem when putting seals on my rocker arm shafts, got 10 of them done when I tried to remove intake shaft on cylinder #2.. it must've been overtorqued and the nut became seized/rusted up on the shaft bolt so when I was trying to unscrew it multiple times the nut got rounded on the inside and now even with a 8mm hex socket it spins through in the nut.
I am able to spin the whole shaft when I turn the 5mm bolt but the nut turns with it.
The 5mm bolt is facing the back of the car, and 8mm nut is facing front of the car. Engine is in the car.

I tried to bang the shaft out of the bore but it's tight in there and doesn't come out even though it turns with hard turning of the bolt itself.
I tried penetrating oil, I tried short hex socket, Allen key, nothing has worked.

Anybody had experience with this? What can I do to get the bolt/nut out of the arm shaft?
Would drilling into the bolt head dislodge the pressure and get the bolt to come out through without unscrewing it from the nut side? Is that my only possible option?

[fred cook]

I suspect that those bolts may be pretty hard so drilling could be a problem. You might look for one of the reverse thread "easy out" tools that have a reverse spiral thread that would bite into the rounded off internal hex. I have seen some that are pretty short and might fit in the working area. Also, it looks as though the bolt was tightened too deeply into the nut thus reducing room for the allen wrench. Perhaps you could grind a concave area on the end of the allen wrench and gain some bite? Good luck!

[koolkozak]

The bolt definitely was pushed in too far into the bit when someone tried to overtorque it probably because that shaft is leaking oil so might have been a a job trying to "fix the leak" without understanding how to works.

[KTL]

I agree with Fred on the fluted extractor. Get one of those and cut it to size so it fits tightly into the recess. This approach is occasionally needed on head stud nuts and it works.

How to remove a stripped head nut

[koolkozak]

The fluted extractors seem too long to get a proper fit and if I cut it then it will not fit into the 8mm but I suspect.
Would this work?
https://www.tooltopia.com/irwin-hanson-vise-grip-53227.aspx?utm_source=google&utm_medium=cpc&utm_campaign=paid_search_google_pla&adpos=1o11&scid=scplpIRW53227&sc_intid=IRW53227&gclid=EAIaIQobChMI4KH8muL92gIViVmGCh0X6wcLEAQYCyAB EgJ4ZPD_BwE

Thanks for the help. I will first try 12point star xzn 8mm bit, bang it in, and try to get grip with that. Will update on results.

[304065]

I managed to strip one when I was assembling my engine.

First, take a file and file down the end of your 8mm allen wrench, so the end is square, not rounded. Sometimes the rounded section prevents the flats from fully engaging the internal wrenching feature.

If you do decide to drill (and I'm not sure how you would, without at least a partial engine drop so that you can get a 1/2" bit and extension into the cam tower from the end-- this will require removing #1 rocker, remember that any chips that make their way into the cam tower will destroy the engine (they will eventually find their way into the oil return tubes).

When I drilled, I stuffed the cam tower full of kimwipes covered in grease, and covered every other surface with grease. This will catch the chips as they fall. I then drilled with a magnet nearby, same idea.

You will be amazed at how hard it is to drill the head off the bolt when it's so easy to strip it.

It can be done, just take your time and focus on chip control. Good luck.

[john walker's workshop]

You use the 5mm bolt head to loosen and tighten, never the 8mm side. The 8mm nut just needs to be held so it doesn't turn in the process. Not that that helps in this case.

[yelcab1]

drop the engine.

[KTL]

As un-luck would have it, it sucks that it's #2 in the middle of the cam housing since that location makes it that much tougher to access the nut with tools. But I would agree that the extractor kit from Tooltopia would be a good approach. They're shorter than the typical longer, tapered fluted extractors like we've used for the head stud nuts. Whatever you do is going to be a makeshift creation to grip the nut at this point, but you certainly need something that will fit into the cam housing so you can grab the nut.

Have you tried hitting it with some heat to free the bolt from the nut? Heat it with your torch and then "cool" it with your choice of penetrating lube. The heat will draw the penetrant into the threads and it will also help break the bond between the threads. Don't be shy about applying a lot of heat. The cam housing will absorb a LOT of heat because it's a big hunk of aluminum. So you need to heat the nut for more than just a few seconds to get it nice & hot.

[Rawknees'Turbo]

This probably isn't possible with the engine installed, but what I did when I rounded one of those internal hexes is I used a 1/4" drive ratchet with a short allen socket and then drove the allen socket into the sripped hex with an air hammer while simultaneously using a wrench on the nut ( air hammer bit placed against the back of the ratchet head - was a two person job).

[koolkozak]

Originally Posted by john walker's workshop

You use the 5mm bolt head to loosen and tighten, never the 8mm side. The 8mm nut just needs to be held so it doesn't turn in the process. Not that that helps in this case.

Yes that is what I was doing except the nut turns with the bolt when I turn the bolt head. And when I hold the nut on the other end to provide counter torque it stripped because it is so seized on the bolt.

[koolkozak]

Originally Posted by KTL

As un-luck would have it, it sucks that it's #2 in the middle of the cam housing since that location makes it that much tougher to access the nut with tools. But I would agree that the extractor kit from Tooltopia would be a good approach. They're shorter than the typical longer, tapered fluted extractors like we've used for the head stud nuts. Whatever you do is going to be a makeshift creation to grip the nut at this point, but you certainly need something that will fit into the cam housing so you can grab the nut.

Have you tried hitting it with some heat to free the bolt from the nut? Heat it with your torch and then "cool" it with your choice of penetrating lube. The heat will draw the penetrant into the threads and it will also help break the bond between the threads. Don't be shy about applying a lot of heat. The cam housing will absorb a LOT of heat because it's a big hunk of aluminum. So you need to heat the nut for more than just a few seconds to get it nice & hot.

I will try your heat method to try to get the penetrant deeper. Thanks

[koolkozak]

Originally Posted by 304065

I managed to strip one when I was assembling my engine.

First, take a file and file down the end of your 8mm allen wrench, so the end is square, not rounded. Sometimes the rounded section prevents the flats from fully engaging the internal wrenching feature.

If you do decide to drill (and I'm not sure how you would, without at least a partial engine drop so that you can get a 1/2" bit and extension into the cam tower from the end-- this will require removing #1 rocker, remember that any chips that make their way into the cam tower will destroy the engine (they will eventually find their way into the oil return tubes).

When I drilled, I stuffed the cam tower full of kimwipes covered in grease, and covered every other surface with grease. This will catch the chips as they fall. I then drilled with a magnet nearby, same idea.

You will be amazed at how hard it is to drill the head off the bolt when it's so easy to strip it.

It can be done, just take your time and focus on chip control. Good luck.

Will try filing the Allen key into a square. Thanks

[koolkozak]

Map/Pro torch ok for heating the nut? How long do you think I should burn it?

[john walker's workshop]

The 8mm nut isn't very deep. I use a 1/4" drive allen socket and long handle ratchet to hold it. The L shaped allen wrench tends to slip and it's hard to keep it square to the nut.

[ed mayo]

Might be time for a little cave man approach since nothing else seems to be working. I have a little collection of various 1/4" sockets that I use for pushing out shafts when working with installed engines, of course normally the bolt is loose, but in your case you did say the shaft turned with torque on the 5 mm end. So pick a socket that will push against the shaft while leaving some amount sticking out past the boss, then stick a pry bar down in between adjacent cylinder head fins as a fulcrum and see if you can push the shaft out, even if just enough to expose the 8 mm nut end. If you can expose the nut end then you have more options.

[koolkozak]

Originally Posted by ed mayo

Might be time for a little cave man approach since nothing else seems to be working. I have a little collection of various 1/4" sockets that I use for pushing out shafts when working with installed engines, of course normally the bolt is loose, but in your case you did say the shaft turned with torque on the 5 mm end. So pick a socket that will push against the shaft while leaving some amount sticking out past the boss, then stick a pry bar down in between adjacent cylinder head fins as a fulcrum and see if you can push the shaft out, even if just enough to expose the 8 mm nut end. If you can expose the nut end then you have more options.

Might this damage the aluminum head as i am prying against it? and would this damage the bore if i try to force it out? Not sure if prying would let it out, but i would have to bang on it from the 5mm bolt head side just worried i might snap the aluminum head fins with all this prying/banging. no?

Update: i tried squaring the allen key...no luck, just spins through even more. tried the heat but not sure if worked because cant get a grip on it. tried a T50 torx star bit and it actually held a little but then my 5mm bolt head stripped. will try the torx bit that would fit the 5mm bolt head next.

i also ordered these...
https://www.amazon.com/gp/product/B01EK3TNLO/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
and
https://www.amazon.com/gp/product/B078RR1N25/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

will try the xzn 12 star next, and then last resort the screw extractors.
and if all those dont work, will attempt drilling into the bolt head and hope it will relieve some pressure to the shaft ends and i can bang it out after.

[safe]

Hammering in a torx-bit usually work when an allen bolt gets rounded.
But I think you will have to drop the engine and removing rockers and other stuff thats in the way.

[911pcars]

Unsure whether your issue is a torqued assembly (nut and bolt) that can't be loosened.....

...or the shaft is stuck inside the cam housing bore despite no tightening tension from the the nut and bolt.

Removing the rocker nut or bolt head is a matter of using one of several techniques to remove either end.

If the shaft is frozen/stuck inside the cam housing because the nut and bolt were previously overtightened, the shaft ends may have physically flared outward. The end result is a shaft that is now larger causing an interference fit.

Heating the Al cam housing could expand the bore enough to drive out the rocker shaft assy. w/o damaging the bore - maybe. Use Mr. Walker's drive and driven sockets to perform this.

Another strategy is to remove the entire cam housing assembly so you have better access/working angles on a work bench. Be aware that the labor cost/time to attempt removal of the stubborn rocker shaft could exceed the cost of a replacement cam housing and rocker arm assy.

Sherwood

[koolkozak]

Update.. tried torx bits/sockets, zxn 12 point star bits, then tried the bolt extractor bits that I posted a link to earlier... nothing worked. Each of the bits kept spinning inside the M5 bolt head it got pretty much rounded after the bolt extractor bit went through it.m and did not manage to grab into it.

I did manage to get the M8 hex socket into the nut end of the shaft assembly and it is holding the nut. Except now the M5 bolt head is completely rounded off. Nothing else I can do except go to my last resort which only works in my head as a theory and I'm praying that it will work.... drilling out the bolt head completely or until it breaks the torquing pressure on the shaft and I'll be able to bang out the shaft without unscrewing the bolt/nut.

Any thoughts?

Here are pics...

M8 hex nut supported with wooden wedges to keep the ratchet straight and pressed into the nut with a good grip



in view of stripped/rounded inside of the M5 bolt head



drill going in at an angle from the back of the car into the bolt head on top intake side cylinder #2



experimented drilling out the bolt head on a spare shaft bolt that i had lying around